Under Linux, the command
Is safe, and only refreshes the packages list stored on the client, to reflect changes that have been made in the repository. OTOH,
Tells the package manager, simply to upgrade all packages, which have newer versions in the lists, from the versions currently installed. In principle, this sounds logically correct. But there is an alternative to this, which is called
The difference is, that ‘dist-upgrade’ is smarter than ‘
upgrade‘ about global changes that might take place, due to changes in the overall Debian Distribution – hence the ‘dist’ – which can affect which directories files and configuration changes need to be stored to.
In practice, ‘d-u’ is always safer than just ‘
upgrade‘, and does everything ‘upgrade’ is supposed to do. Therefore, we generally give the command